[jcslocum]

With a low use tool like a torque wrench, warranty isn't what you need to concerned with. Accuracy and repeatability is what's needed. If the mechanism that measures and indicates torque goes off you won't know it until you are breaking stuff or have stuff leaking or falling off. That's why it's important to buy a good one that you have confidence in the maker and treat it right. The cheaper and most dependable are the old beam type that really have no moving parts. The clicker types and springs and cams and the electro is, well they have electrons that can get out.

I no longer work on cars professionally and haven't for a while, but bolted connections are very important. Luckily designers have good knowledge of how the joint will work and design around the ability for it to be done right.